Antibiotic use is on the decline, according to new government data. / PhotoDisc

by Kim Painter, Special for USA TODAY

by Kim Painter, Special for USA TODAY

Antibiotic use in the United States is dropping, but it is dropping most slowly in states that use the drugs the most â?? widening regional gaps that may be putting people in some Southeastern states at heightened risk for infections that no longer respond to antibiotics, a new analysis shows.

Researchers aren't just guessing at the danger: They also have new data showing that urinary tract infections have became more resistant to antibiotics and that the problem is worst in regions where use is highest.

"We are seeing a widening gap between states," says Ramanan Laxminarayan, director of the private Center for Disease Dynamics, Economics & Policy, Washington, D.C. Prescription records show that people in Kentucky, West Virginia, Tennessee, Mississippi, and Louisiana took about twice as many antibiotics as people in Alaska, Hawaii, California, Oregon, and Washington in 2010, says a report released by the center today.

Lab reports show urinary tract infections were 30% more likely to resist antibiotic treatment in 2010 than in 1999.

The report is one of several coming this week as government and private groups unite to call for more action on what they say is a growing threat: Drugs for many bacterial infections are becoming ineffective because they are so often taken when they are not needed - allowing bugs that cause everything from pneumonia to sexually transmitted diseases to adapt and survive future attempts at treatment.

Much of the overuse is for colds, flu and sore throats caused by viruses - illnesses that antibiotics can't help.

Why antibiotics use differs by state is unclear. The South has higher rates of poverty, smoking and chronic illnesses, and some of those factors might lead doctors to prescribe more antibiotics for respiratory illnesses because they are worried about complications, says Nancy Morden, an assistant professor at the Dartmouth Institute for Health Policy & Clinical Practice in New Hampshire.

But a recent study of Medicare patients found that differences in gender, age, race and health status did not explain regional differences in antibiotic prescribing very similar to those found in the new study, says Yuting Zhang, a researcher at the University of Pittsburgh, who led the Medicare study.

In any case, there's no evidence the extra antibiotics help or that lower use hurts people, Laxminarayan says. He says states with the lowest use typically devote the most public health resources to teaching doctors and patients to use the drugs correctly.

Many are taking heed: Nationwide antibiotic use dropped 17% between 1999 and 2010, the report says. And a new survey out today from the Pew Charitable Trusts and the U.S. Centers for Disease Control and Prevention (CDC) shows 79% of adults know they can harm their own health by taking unneeded antibiotics.

But just 47% know that doing so could harm others, including family members and people in their communities who might pick up their hard-to-treat bugs, says Allan Coukell, director of medical programs for Pew.

Antibiotic resistance is not just a personal or even a regional issue, says Jeffrey Levi executive director of the Trust for America's Health in Washington, D.C.: "We need to to establish some standards of practice across the country," he says. Resistant bacteria spread from person to person and place to place, he says, "and there are consequences for everybody."

Levi's group is one of two dozen health organizations that signed a consensus statement with the CDC, released today, calling for consumers, healthcare workers, policy makers and pharmaceutical companies to work together to make better use of existing antibiotics and develop new ones.

The statement also calls for limiting the use of antibiotics in animals raised for food.

"Antibiotics have saved millions of lives and transformed modern medicine," but "how we use these precious drugs must fundamentally change," says Arjun Srinivasan, who directs a program to prevent healthcare-related infections at the CDC. Srinivasan spoke during a teleconference kicking off an annual campaign to raise awareness of proper antibiotic use.